The stock market is on bubble watch — And unlike the dotcom era, this time the whole market is expensive

Stock indices forged ahead to make new highs before escalating political tensions between the US and North Korea spurred some mid-week selling. Business Insider CEO Henry Blodget discusses the many yellow flags that have been raised about the sustainability of the equity rally. Among them is the lofty level of stock valuations, which are the most extended since the tech bubble. That's flashing warning signs about how long the rally can continue. And unlike the dotcom era, all sectors are stretched right now, not just tech.